1. The Field of the Invention
The present invention relates generally to optical transceivers and optical transceiver host computing systems (hereinafter referred to simply as “host”). More specifically, the present invention relates to calibrating digital diagnostic information of the optical transceiver prior to reporting the calibrated information to the host.
2. The Relevant Technology
Computing and networking technology have transformed our world. As the amount of information communicated over networks has increased, high speed transmission has become ever more critical. Many high speed data transmission networks rely on optical transceivers and similar devices for facilitating transmission and reception of digital data embodied in the form of optical signals over optical fibers. Optical networks are thus found in a wide variety of high speed applications ranging from as modest as a small Local Area Network (LAN) to as grandiose as the backbone of the Internet.
Typically, data transmission in such networks is implemented by way of an optical transmitter (also referred to as an electro-optic transducer), such as a laser or Light Emitting Diode (LED). The electro-optic transducer emits light when current is passed there through, the intensity of the emitted light being a function of the current magnitude through the transducer. Data reception is generally implemented by way of an optical receiver (also referred to as an optoelectronic transducer), an example of which is a photodiode. The optoelectronic transducer receives light and generates a current, the magnitude of the generated current being a function of the intensity of the received light.
Various other components are also employed by the optical transceiver to aid in the control of the optical transmit and receive components, as well as the processing of various data and other signals. For example, such optical transceivers typically include an electro-optic transducer driver (e.g., referred to as a “laser driver” when used to drive a laser signal) configured to control the operation of the optical transmitter in response to various control inputs. The optical transceiver also generally includes an amplifier (e.g., often referred to as a “post-amplifier”) configured to perform various operations with respect to certain parameters of a data signal received by the optical receiver. A controller circuit (hereinafter referred to the “controller”) controls the operation of the laser driver and post amplifier.
Additionally, the controller may also include various sensors that are capable of measuring transceiver operational parameters. There may also be sensors coupled to the laser driver, the post-amplifier and other transceiver components. These operational parameters may include temperature, voltage to the transceiver, laser bias current, receive and transmit power, and the like.
During the operation of the optical transceiver, it is often useful to perform diagnostics of the various operational parameters. A typical way diagnostics are performed is to have the sensors measure an operational parameter value and send the value to an analog to digital converter, which may be within the controller or may be a separate transceiver component. The analog to digital converter converts the value to a digital signal and reports the value to a host computing system coupled to the transceiver module. This allows a user or the host to then evaluate the various operational parameters.
However, the digitally converted signals that are reported to the host often do not represent the actual measured analog values. This is due to some predictable signal corruption that is often inherent in the analog to digital conversion.
One way to alleviate these problems is to have the host perform calibration on the digital values it receives from the transceiver analog to digital converter. The transceiver manufacturer would provide the user with an equation for the digital output of an ideal analog to digital converter with no predictable error. The user would then be able to have the host use the equation to perform a calibration on the digitally converted signal. In this way, reliable digital diagnostics values can be obtained.
However, having the host perform the calibration on the digital diagnostics information uses valuable host resources that are necessary for other host operations. This may affect the overall speed and performance of the calibration operation. This is especially true for a host that supports multiple optical transceivers. In addition, having the host perform the calibration often requires a larger or faster host microprocessor or adding additional processors.
Therefore, what would be advantageous is an optical transceiver that is capable of performing calibration of digital diagnostics internally prior to reporting the diagnostic values to the host.